I may be misunderstaneding the posts but I know that
Newark airport international arrivals area where one
collects the internationally checked luggage does have
a fee for obtaining a cart. However, the traveler may
use a credit card and often there is an attendant at
the cart installation collecting dollar bills and
giving people a cart from the device. As noted in the
other posts, though, those machines used a coin.
There was no mention if one could also use a credit
card.

Something interesting happened to me several weeks
ago. After I had arrived at Newark Liberty Airport,
I passed through security and was then inside the
airport and accessed the cash machine using my U.S.
credit card to obtain dollars. My credit card charged
me a fee for being in a foreign country, even though
I was in good old Newark. I guess once one goes through
to the other side of security, one is no longer in New
Jersey!!